PCB structure for scope unit of electronic endoscope

ABSTRACT

A scope unit of an electronic endoscope system is provided with first and second printed circuit boards respectively formed with first and second circuit sections. The first printed circuit board is fixed with respect to the second printed circuit board at a plurality of fixing areas. At least one connector is connected with the at least one corresponding connector when the first printed circuit board is piled on the second printed circuit board. The at least one connector and the at least one corresponding connector are aligned between two of the plurality of fixing areas and substantially on a line connecting the two of the plurality of fixing areas.

TITLE OF THE INVENTION

[0001] PCB Structure for Scope Unit of Electronic Endoscope

BACKGROUND OF THE INVENTION

[0002] The present invention relates to an electronic endoscope system,and more particularly to a PCB (Printed Circuit Board) structure for ascope unit of the electronic endoscope system.

[0003] A medical electronic endoscope is generally provided with aprocessor having a light source, image processing unit and the like, andan electronic scope (a scope unit) having a portion to be inserted in ahuman body. The electronic scope has a light guide, which receives thelight emitted by the light source from the processor and illuminatesinside the human body, and a CCD (Charge Coupled Device) which capturesan image of the illuminated portion.

[0004] In such an electronic endoscope, electronic circuits areprovided. Typically, an electronic circuit is installed inside a sectionof the electronic scope in a form of a PCB. In a conventional electronicscope, the PCB is formed of a single substrate having a relatively largearea. Generally, such a PCB is provided at a connection section at whichthe scope unit is connected to the processor. Since the PCB has arelatively large area, the connection section of the endoscope unitbecomes large. The large scope unit is troublesome in handling, i.e., ineach of operating, carrying and storage, the larger scope unit isburdensome to the operator.

[0005] Conventionally, a structure, in which two PCBs havingsubstantially the same size are piled, has been known. In such astructure, the circuit is divided into two portions, which are formed onthe two PCBs respectively.

[0006] In such a PCB structure, in order to electrically connect thecircuits respectively formed on the two PCBs, a connecting member suchas a connector should be provided. Hereinafter, such a connectorprovided between two facing PCBs will be referred to as an inter-PCBconnector. Typically, a location of such an inter-PCB connector isdetermined based on the circuit patterns of the PCBs. That is,arrangement of electrical elements on the circuits are determined first,and then based on the position of the electrical elements, the numberand positions of the inter-PCB connectors are determined so that, forexample, distances between the terminals of the elements andcorresponding connectors become relatively short.

[0007] Further, the inter-PCB connector is mounted on a surface of thePCB. Therefore, if two PCBs are integrally piled, the positionalrelationship between the two PCBs is carefully determined so thatsubstantially even force is applied to all the inter-PCB connectors inthe substantially same direction so that the inter-PCB connectors and/orthe PCBs themselves will not be damaged. Therefore, the conventionalstructure described above requires a worker for great care, which causesemotional toll on the worker.

[0008] Further, when one of the PCBs is replaced, the fixed condition ofthe two PCBs is removed. In such a case, a force applied to pull out oneconnector may cause another force in an unintentional direction toanother connector. In such a case, a portion of a printed circuitpattern may be exfoliated or a terminal of an inter-PCB connector may bebroken at a soldered position or the like.

SUMMARY OF THE INVENTION

[0009] The present invention is advantageous in that an improved PCBstructure is provided, with which fixing and releasing operation of twoPCBs can be executed easily, and further, when the two PCBs areintegrally fixed, all the inter-PCB connectors are firmly sandwichedbetween the PCBs.

[0010] According to an aspect of the invention, there is provided aprinted circuit board structure for a scope unit of an electronicendoscope system, which is provided with a first printed circuit boardformed with a first circuit section, a second printed circuit boardformed with a second circuit section, the first printed circuit boardbeing piled on the second printed circuit board with a predeterminedclearance therebetween. The first printed circuit board is fixed withrespect to the second printed circuit board at a plurality of fixingareas. With this structure, at least one connector is provided on thefirst printed circuit board, and at least one corresponding connector isprovided on the second printed circuit board. The at least one connectoris connected with the at least one corresponding connector when thefirst printed circuit board is piled on the second printed circuitboard. The at least one connector and the at least one correspondingconnector are aligned between two of the plurality of fixing areas andsubstantially on a line connecting the two of the plurality of fixingareas.

[0011] According to a further aspect of the invention, there is providedan electronic endoscope system having a scope unit and processor, thescope unit employing a printed circuit board structure. In this system,the above-described printed circuit board structure may be employed.

[0012] With this configuration, the firm connection between the at leastone connector and at least one corresponding connector is ensured, andsubstantially even force is applied to the at least one connector andcorresponding connector.

[0013] Optionally, the two fixing areas and the at least one connectorand the at least one corresponding connector may be located atperipheral portions of either of the first printed circuit board and thesecond printed circuit board.

[0014] Further optionally, each of the first printed circuit board andsecond printed circuit board has a liner side, the peripheral portionbeing close to the liner sides of the first and second printed circuitboard.

[0015] Further, the scope unit may be provided with an imaging elementto be driven to capture an image and output an image signal. The firstcircuit section is configured to receive an output signal of the imagingelement and processes the received signal to generate an analog imagesignal, and the analog image signal is transmitted to the processorunit. Further, the second circuit section may be configured to controlat least the imaging element and the first circuit section.

[0016] In another aspect, the first circuit section may be a digitalcircuit and the second circuit may be a analog circuit.

[0017] In this case, the second circuit section may be grounded. Withthis configuration, noises can be effectively reduced.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0018] FIGS. 1A-1C are a plan view, a front view and a side view of thePCB structure according to an embodiment of the invention, respectively;and

[0019]FIG. 2 is a block diagram illustrating an electrical configurationof the electronic endoscope according to the embodiment of theinvention.

DETAILED DESCRIPTION OF THE EMBODIMENT

[0020] FIGS. 1A-1C are a plan view, a front view and a side view of thePCB structure, respectively. The PCB structure is employed in anelectronic endoscope system 100 (hereinafter, occasionally referred toas endoscope system) according to an embodiment of the invention. FIG. 2is a block diagram illustrating an electrical configuration of theelectronic endoscope system 100.

[0021] The endoscope system 100 includes a scope unit 100 a, a processorunit 100 b and a monitor 100 c. A CCD 20 is provided at a tip end(distal end) of the scope unit 100 a.

[0022] Although not shown in the drawings, the processor unit 100 b isprovided with power unit for providing electrical power to the connectedscope unit 100 a, a light source unit for providing light to the scopeunit 10 a for illuminating an object to be observed, and an imageprocessing unit that processed an image signal captured by the CCD 20and transmitted from the scope unit.

[0023] The scope unit 100 a includes a driving unit 10 which controls anelectrical operation of the scope unit 100 a. The driving unit 10 isdivided into two (i.e., first and second) circuit sections S1 and S2.

[0024] The first circuit section S1 mainly controls an entire operationof the scope unit 10 a and is formed as a digital circuit. The firstcircuit section S1 includes a CPU 1, EEPROM 2, a masking unit 3 and adip switch 4.

[0025] Further, the second circuit section S2 mainly processes an imagesignal output by the CCD 20 and generates an analog video signal. Thesecond circuit section S2 is formed as an analog circuit, which includesa DSP (Digital Signal Processor), a regulator 6 and the like. Theregulator 6 functions as a main portion of a power circuit of the scopeunit 100 a. It should be noted that, although not indicated in thedrawings, the first circuit section S1 has fewer elements than thesecond circuit section S2.

[0026] As shown in FIGS. 1A-1C, the driving unit 10 includes two PCBs(printed circuit boards) 10A and 10B having a piled structure.

[0027] According to the embodiment, the first and second circuitsections S1 and S2 are formed on the PCBs 10A and 10B, respectively.

[0028] The driving unit 10 is provided at a portion, inside the scopeunit 100 a and close to a part of the scope unit 100 a to be connectedwith the processor unit 100 b. Since the driving unit 10 can bedownsized as described above, the part of the scope unit 100 a to beconnected with the processor unit 100 b can be downsized. According tothe embodiment, the scope unit 100 a can be quite operative, andunnecessary burden will not be provided to a user of the scope unit 100a.

[0029] As shown in FIGS. 1A-1C, the first PCB 10A is provided with aconnector CN1 for connecting the first circuit section S1 with theprocessor 100 b, and inter-PCB connectors CN3 a and CN4 a for connectingthe first circuit section S1 with the second circuit section S2.

[0030] The second PCB 10B is provided with a connector CN2 forconnecting the second circuit section S2 with the processor 100 b, andinter-PCB connectors CN3 b and CN4 b respectively corresponding to theinter-PCB connectors CN3 a and CN4 a.

[0031] It should be noted that each of the first PCB 10A and second PCB10B has a rectangular shape, and the first PCB 10A is formed to besmaller at least in a direction parallel to one side of the rectangularshape. Further, the first and second PCBs 10A and 10B are piled suchthat both end side portions of the second PCB 10B have areas which arenot covered with the first PCB 10A.

[0032] It should be noted that, according to the embodiment, the firstPCB 10A is provided with fewer elements than the second PCB 10B, andtherefore, the first PCB 10A can be made smaller than the second PCB10B. Although not shown in the drawings, the center of the first PCB 10Aand the center of the second PCB 10B substantially coincide with eachother.

[0033] A clearance unless circuity shorting between the first and secondPCBs 10A and 10B is determined in accordance with the height, withrespect to the second PCB 10B, of an element on the second circuitsection S2 (i.e., the second PCB 10B) within an area covered with thefirst PCB 10A. According to the embodiment, the clearance is determinedsubstantially the same as the height of the connectors CN3 and CN4.

[0034] The width of the clearance is defined by the height of spacers 7Athrough 7D. Each of the spacers 7A, 7B, 7C and 7D has a cylindricalshape formed with two threaded holes at end portions thereof.

[0035] By screwing screw 8A and 9A, with the first PCB 10A, the spacer7A, and the second PCB 10B therebetween, screwing 8B and 9B with thefirst PCB 10A, the spacer 7B and the second PCB 10B therebetween,screwing 8C and 9C, with the first PCB 10A, the spacer 7C and the secondPCB 10B therebetween, screwing 8D and 9D with the first PCB 10A, thespacer 7D and the second PCB 10B therebetween, the first and second PCBs10A and 10B are integrally secured with the necessary clearancetherebetween.

[0036] It should be noted that, according to the embodiment, the spacers7A-7D has a cylindrical shape. However, the shape of the spacers 7A-7Dneed not be limited to the cylindrical shape, and any other suitableshape can be employed.

[0037] Hereinafter, portions at which the PCBs 10A and 10B and thespacers 7A-7D are fixed will be referred to as fixed areas. Thus,reference numerals 8A-8D, and 9A-9D represent the fixed areas as well asthe screws. That is, the first PCB 10A has fixing areas 8A-8D, and thesecond PCB 10B has four fixing areas 9A-9D. As shown in FIG. 1A, thefixing areas 8A-8D are located at corners of the rectangular shape ofthe first PCB 10A.

[0038] The second PCB 10B is secured in a casing G (see FIG. 1C)provided in the scope unit 100 a via conductive members 11A-11D whichcombine the ground pattern of the second circuit section S2 to the flameground of the casing G. The second circuit section S2 formed on thesecond PCB 10B may be affected by noises relatively easily since itincludes an analog circuit. Therefore, by using the conductive members11A-11D for supporting the second PCB 10B to ground the second circuitsection S2, the noises can be removed by the electromagnetic shieldingand a stable operation of the second circuit section S2 is ensured.

[0039] Next, the inter-PCB connectors CN3 a, CN3 b, CN4 a and CN4 b willbe described in detail.

[0040] As shown in FIG. 1A, the inter-PCB connectors CN3 a and CN4 a arealigned along positions close to the right-hand side of the rectangularshape of the first PCB 10A in FIG. 1A. Specifically, the right-handsides (in FIG. 1A) of the inter-PCB connectors CN3 a and CN4 a arelocated between the two fixing areas 8C and 8D and substantially on aline connecting the fixing areas 8C and 8D.

[0041] The inter-PCB connectors CN3 b and CN4 b are located at positionscorresponding to the inter-PCB connectors CN3 a and CN4 a, respectively.That is, the right-hand sides (in FIG. 1A) of the inter-PCB connectorsCN3 b and CN4 b are located between the two fixing areas 9C and 9D andsubstantially on a line connecting the fixing areas 9C and 9D.

[0042] With the above configuration, the following advantages can beachieved.

[0043] When the PCBs 10A and 10B are fixed, since the connectors CN3 a,CN3 b, CN4 a and CN4 b are aligned on a line connecting the fixing areas8C, 8D, 9C and 9D, substantially even force can be applied to theconnectors CN3 a, CN3 b, CN4 a and CN4 b. Thus, the connectors can befirmly connected without being damaged. Further, when the connectors CN3a, CN3 b, CN4 a and CN4 b are connected, positional relationshipsbetween the PCBs 10A and 10B and the spacers 7A-7D can be automaticallyadjusted. Therefore, the PCBs 10A and 10B can easily be fixed with eachother.

[0044] After the screws 8A-8D and 9A-9D are fastened, since theconnectors CN3 a, CN3 b, CN4 a and CN4 b are located on a lineconnecting the fixing areas 8C and 8D (or 9C and 9D), the firmconnection is maintained, and the connectors CN3 a and CN4 a cannot bedisconnected from the connectors CN3 b and CN4 b, respectively, even ifunintentional force or vibration is applied.

[0045] Further, when the fixation between the PCBs 10A and 10B isremoved, the even force may be kept applied to all the connectors. Thus,the force in an unintentional direction will not be applied, and all theinter-PCB connectors can be disconnected without damage.

[0046] Hereinafter, with reference to FIG. 2, an operation of theendoscope system 100 will be described.

[0047] The CPU 1 controls the entire operation of the scope unit 10 a.The CPU 1 drives the scope unit 100 a in accordance with settingstransmitted from external devices (not shown) and/or settings of the DIPswitch 4. The CPU 1 transmits/receives signals to/from the secondcircuit section S2 through the inter-PCB connectors CN3 a, CN3 b, CN4 aand CN4 b. Further, the CPU 1 transmits a timing signal to the processor100 b through the connector CN1. The CPU 1 retrieves necessary data fordriving the scope unit 100 a from the EEPROM 4.

[0048] The DSP 5 outputs a timing signal for the CCD 20, receives theimage signal from the CCD 20, and generates analog image signals, i.e.,color difference signal C and brightness signal Y. The color differencesignal C and the brightness signal Y are amplified and transmitted twothe processor unit 100 b through the connector CN2.

[0049] According to the embodiment, the CPU 1 receives masking datatransmitted from the masking unit 3, and transmits a mask processingsignal to the DSP 5. Thus, when the color difference signal C and thebrightness signal Y are generated, the masking process is simultaneouslyperformed. By the masking process, a peripheral portion of an imagedisplayed on the monitor 100 c is masked and displayed as a black area,which improves appearance of the displayed image.

[0050] The electrical power is supplied from the processor unit 100 b tothe regulator 6 through the connector CN2. The regulator 6 converts thesupplied voltage into optimum voltages for electrical units inside thescope unit 100 a, respectively, and applies the converted voltages torespective electrical units. As described above, the power source unitincluding the regulator 6 is provided on the second PCB 10B bearing thesecond circuit section S2. Operation of the analog circuit easilybecomes unstable when noises are applied and/or predetermined voltage isnot applied. Thus, according to the embodiment, the power source unit islocated within the analog circuit (i.e., the second circuit section S2),so that the voltages are applied to respective units of the secondcircuit section S2 before being affected by noises.

[0051] It should be noted that the voltages are supplied to units in thefirst circuit section S1, e.g., the CPU 1, through the second PCB 10Band the inter-PCB connectors CN3 a, CN3 b, CN4 a and CN4 b. Since theunits of the digital circuit (i.e., the first circuit section S1) remainstable if fluctuation of voltages and/or noises are generated, even iflines through which voltages are applied to the second circuit sectionS2 are relatively long, it is expected that the scope unit 100 aoperates stably.

[0052] By dividing an entire circuitry into the digital circuit and theanalog circuit, and providing the same on different PCBs 10A and 10B, itbecomes easier to judge which PCB malfunctions when the entire circuitrymalfunctions. Further, in such a case, only the PCB having the defectsmay be replaced, thereby lowering maintenance costs.

[0053] In particular, since elements of a digital circuit improves inquality quickly, the PCB bearing the digital circuit may be replacedwith another PCB of a higher version. On the other hand, the analogcircuit may not improve as quickly. For example, frequency settings ofthe DSP 5 is adjusted to an individual difference of the CCD 20. If theanalog circuit is provided on the same PCB bearing as the digitalcircuit, the analog circuit should be replaced when the digital circuitis replaced. In such a case, the adjustment of the elements of theanalog circuit as exemplified above should be performed, which requiresa troublesome process.

[0054] According to the above-described embodiment, since the digitalcircuit and the analog circuit are provided on different PCBs, the aboveproblem can be avoided.

[0055] It should be noted that the foregoing is an exemplary embodiment,and the present invention is not limited to the above-describedconfiguration. Rather, the structure may be modified in various wayswithout departing from the scope of the invention.

[0056] For example, the size and shape of the PCBs are not limited tothe PCBs described above. The two PCBs may have different shape. Forexample, the shape of the second PCB 10B, which is secured to the casingG, may be determined to correspond to other elements provided in thescope unit 100 a. It should be noted that, even when the shape ischanged, the inter-PCB connectors may preferably be located atperipheral portions in view of fixing the two PCBs.

[0057] In the embodiment, the two PCBs are formed with digital andanalog circuits, respectively. However, the invention is not limited tosuch a configuration. For example, elements which may be replacedfrequently may be provided on one PCB and elements which may not bereplaced so frequently may be provided on the other PCB.

[0058] In the above-described embodiment, there are two inter-PCBconnectors. However, the number of the connectors need not be limited totwo, and one or more than three connectors may be provided to each PCB.

[0059] In the above-described embodiment, the light source is providedin the processor unit 100 b. However, the light source need not alwaysbe provided to the processor 100 b, and another configuration, forexample, an LED provided in the vicinity of the CCD 20 may be used.

[0060] Although the embodiment is described with reference to a medicalendoscope system, it should be appreciated that the invention is alsoapplicable to industrial endoscope systems.

[0061] It should be noted that, according to the embodiment, the fixingareas are located at four corners of the rectangular shape. However, theinvention need not be limited to such a configuration. The shape of thePCBs can be modified, and therefore, the fixing areas need not belocated at corners of the PCBs. Further, even if the PCBs haverectangular shape, the location of the fixing areas may be modified. Inorder to ensure that substantially even force is applied to one of moreconnectors, the one or more connectors may be located between two fixingareas and aligned on a line connecting the two fixing areas regardlessof the location thereof. On the other hand, in view of the operabilityin connecting/disconnecting the corresponding connectors provided onboth PCBs, it is preferable that the connectors are located atperipheral portion. Thus, the location of the fixing areas andconnectors may be determined with balancing the above.

[0062] The present disclosure relates to the subject matter contained inJapanese Patent Application No. 2001-382268, filed on Dec. 14, 2001,which is expressly incorporated herein by reference in its entirety.

What is claimed is:
 1. A printed circuit board structure for a scopeunit of an electronic endoscope system, said structure comprising: afirst printed circuit board formed with a first circuit section; asecond printed circuit board formed with a second circuit section, saidfirst printed circuit board being piled on said second printed circuitboard with a predetermined clearance therebetween, said first printedcircuit board being fixed with respect to said second printed circuitboard at a plurality of fixing areas; at least one connector provided onsaid first printed circuit board; at least one corresponding connectorprovided on said second printed circuit board, said at least oneconnector being connected with said at least one corresponding connectorwhen said first printed circuit board is piled on said second printedcircuit board, wherein said at least one connector and said at least onecorresponding connector are aligned between two of the plurality offixing areas and substantially on a line connecting the two of theplurality of fixing areas.
 2. The structure according to claim 1,wherein the two fixing areas and the at least one connector and said atleast one corresponding connector are located at peripheral portion ofeither of said first printed circuit board and said second printedcircuit board.
 3. The structure according to claim 2, wherein each ofsaid first printed circuit board and second printed circuit board has aliner side, said peripheral portion being close to the liner sides ofsaid first and second printed circuit board.
 4. The structure accordingto claim 1, wherein said scope unit has an imaging element to be drivento capture an image and output an image signal, wherein said firstcircuit section receives an output signal of the imaging element andprocesses the received signal to generate an analog image signal, theanalog image signal being output to a processor unit, and wherein saidsecond circuit section controls at least the imaging element and saidfirst circuit section.
 5. The structure according to claim 1, whereinsaid first circuit section is a digital circuit and said second circuitsection is a analog circuit.
 6. The structure according to claim 5,wherein said second circuit section is electromagnetically shielded. 7.An electronic endoscope system having a scope unit and a processor, saidscope unit employing a printed circuit board structure, said structurecomprising: a first printed circuit board formed with a first circuitsection; a second printed circuit board formed with a second circuitsection, said first printed circuit board being piled on said secondprinted circuit board with a predetermined clearance therebetween, saidfirst printed circuit board being fixed with respect to said secondprinted circuit board at a plurality of fixing areas; at least oneconnector provided on said first printed circuit board; at least onecorresponding connector provided on said second printed circuit board,said at least one printed circuit board being connected with said atleast one corresponding connector when said first printed circuit boardis piled on said second printed circuit board, wherein said at least oneconnector and said at least one corresponding connector are alignedbetween two of the plurality of fixing areas and substantially on a lineconnecting the two of the plurality of fixing areas.
 8. The systemaccording to claim 7, wherein the two fixing areas and the at least oneconnector and said at least one corresponding connector are located atperipheral portion of either of said first printed circuit board andsaid second printed circuit board.
 9. The system according to claim 8,wherein each of said first printed circuit board and second printedcircuit board has a liner side, said peripheral portion being close tothe liner sides of said first and second printed circuit board.
 10. Thesystem according to claim 7, wherein said scope unit has an imagingelement to be driven to capture an image and output an image signal,wherein said first circuit section receives an output signal of theimaging element and processes the received signal to generate an analogimage signal, the analog image signal being output to the processorunit, and wherein said second circuit section controls at least theimaging element and said first circuit section.
 11. The system accordingto claim 7, wherein said first circuit section is a digital circuit andsaid second circuit section is a analog circuit.
 12. The systemaccording to claim 5, wherein said second circuit section iselectromagnetically shielded.